JP2900776B2 - Distance measurement device using fixed data pattern - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention uses a data clock and a frame synchronization pattern required for data transmission in a mobile communication or satellite communication system for transmitting and receiving a data pattern, or a spread spectrum communication system. The present invention relates to a distance measuring device for measuring a reciprocating distance between a mobile object or a flying object and a base station using a PN code clock for spread spectrum and a transmission / reception timing of the PN code used in the method.

[0002]

2. Description of the Related Art FIG. 3 shows a frame synchronization timing in a transmission / reception data transmission system, in which a difference in generation timing of a frame synchronization pattern (a type of fixed data pattern) between a transmission side and a reception side is measured by a delay time measurement system. FIG. 4 is a configuration diagram of a distance measuring device used, and FIG. 4 is a time chart showing signals of respective units of the distance measuring device.

The delay time measuring function in FIG. 3 is based on the transmission timing of the transmission frame synchronization pattern h,
A measurement gate i as shown in FIG. 4 is formed between the timing at which the frame synchronization pattern m is detected on the receiving side, and the number of high-speed reference clocks j is counted while the measurement gate i is open. The width of i, that is, the transmission / reception frame synchronization timing difference is measured. When the number of periods of the high-speed reference clock j is f _REF , the width of the measurement gate i is T, and the value of the measurement count k is N, the following relationship is obtained: T = (1 / f _REF ) · N “SEC” Therefore, the round trip distance R with respect to the measurement delay time T is obtained as follows.

R = (speed of light) * T “m”

[0005]

In the delay time measuring method shown in FIG. 3, a high-speed frequency of the reference clock j is required to improve the distance measuring resolution, that is, the delay time measuring resolution. Requires a counter 7 that counts the wave number of the high-speed reference clock j to operate at a high speed and have a long counter length. Normally, if the counter length is increased, it is difficult to handle a high-speed reference clock due to the problem of the propagation time of the carry signal that propagates the change of the least significant digit to the most significant digit, thus increasing the maximum distance measurement range and increasing the measurement resolution. It has been difficult to measure improvements.

In the method of measuring the gate width by opening the measurement gate at a transmission event (input event h) and closing the measurement gate at a reception event (reference event m),
It is necessary to make a waiting time necessary for performing the next measurement, and the disadvantage that measurement cannot be performed during this time is inevitable.

[0007]

Means for Solving the Problems] claims of the present invention to solve the aforementioned problem 1, a data pattern based on the transmission timing of fixed data pattern from the transmitting side transmits to the transmission line, the receiving side Recovering the data clock and detecting the fixed data pattern, measuring the delay time between the detection of the fixed data pattern and the transmission timing to measure the delay time generated in the transmission path, In a distance measurement device that measures the distance of the transmission line based on a delay time, a count value obtained by sampling the content of a transmission-side fixed data counter at a detection timing of a reception-side fixed data pattern is used.
Coarse delay time from the value divided by the transmission clock frequency
And obtains the phase of the clock on the transmission side at the reception fixed data pattern detection timing by the means for measuring .
Get the high-resolution delay time from the data, using the fixed data pattern and outputting the distance calculated by combining the said high-resolution time delay between the coarse delay time as the distance of the transmission path distance Provide a measuring device. The second aspect of the present invention relates to a data transmission method.
Applied to communication systems that transmit and receive data more,
The data pattern is a frame synchronization pattern, and
The constant data counter is a frame counter
The fixed data pattern according to claim 1 is used.
Provided is a distance measuring device.

[0008]

The delay time measuring means of the present invention counts the transmission-side frame synchronization pattern (fixed data pattern) interval, that is, the frame size, with the transmission data clock, and samples the contents of this counter at the reception-side frame synchronization pattern detection timing. In addition, there is a system for measuring the delay time using the transmission side data clock as a reference signal (corresponding to the reference clock j in FIGS. 3 and 4). Assuming that the transmission side data clock frequency is f _TX and the transmission frame size is N, a delay time measuring instrument having a delay time measurement resolution (1 / f _TX ) and a maximum measurement delay time range (N / f _TX ) can be realized.

In general, the resolution in delay time measurement cannot be improved simply by using the transmission data clock as the reference signal. However, by having the phase measurement function of measuring the phase of the transmission data clock at the reception frame synchronization detection timing, the resolution in delay time measurement can be improved.

Assuming that the measurement phase resolution is δθ and the measurement phase is θ, the measurement delay time resolution ｛(1 / f _TX ) · (δθ / 2
π)}, a delay time measuring device having a maximum measurement delay time range (1 / f _TX ), and by combining the measured value with the measured value, measurement delay time resolution {(1 / f _TX ) · (δθ / 2π)}, It is possible to realize a delay time measuring device having a maximum measurement delay time range (N / f _TX ).

Assuming that the measured phase difference is θ and the wave number count sampling value is X, the measured delay time T can be calculated by the following equation.

T = (θ + 2πX) / (2πf _TX ) “SEC” The present invention employs a method of sampling the value of the transmission-side frame counter and sampling the phase of the transmission-side data clock when detecting the reception frame synchronization pattern. ing. Therefore, the conventional device of FIG. 3 was inevitable.
The device of the present invention does not have the disadvantage of having a non-measurement band necessary for the next measurement, and also has a measurement value θ (k−
1) By holding the value of X (k-1), an additional function of measuring the period P between received frames can be obtained.

P = ｛θ (k) + 2πX (k) −θ (k−
1) + 2πX (k-1)｝ / (2πf _TX )

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a configuration of an embodiment of the present invention,
FIG. 2 is a time chart of signals of each part in the embodiment of FIG.

A transmission data clock d generated by a reference clock generation source (also serving as a data generator) 1 is transmitted to a frame pattern generator 2 and a frame counter 9. The frame generator 2 receives the transmission data clock d and the data D1, generates a transmission data pattern D2 including a frame synchronization pattern, and transmits the transmission data pattern D2 to the transmission path 3. The bit synchronization circuit 4 reproduces a data clock from the reception data pattern, transmits the reproduction clock a and the reproduction data D3 to the frame synchronization section 5, and detects the position of the frame synchronization pattern in the reception data pattern.

The frame counter 9 counts a transmission data clock d from the reference clock generation source 1, and outputs a transmission frame timing R from the frame pattern generator 2.
, Thus forming a ring counter. The detection timing of the reception frame synchronization pattern (reception event b) of the frame synchronization unit 5 described above
0, where the transmission frame count value c is sampled, thereby realizing a delay time measuring / decomposing function (1 / f _TX ) and a delay time measuring device having a maximum measurement delay time range (N / f _TX ).

On the other hand, the transmission data clock d is stored in the waveform memory 111 of the recording capacity T, and the reception frame detection timing b is transmitted to the waveform memory 111 via the T / 2 delay circuit 112, and the transmission data clock d Is terminated. Therefore, the waveform memory 111 stores the section [+
T / 2, -T / 2], the waveform of the transmission data clock d is stored. The numerically controlled oscillator 113 is an oscillator that generates SIN and COS complex signals (e and f in FIG. 2) having a phase of zero at the center of the data in the waveform memory 111 and the same frequency as the transmission data clock d. . The complex multiplier 114 performs the following calculation between the contents of the waveform memory 111 and the output of the numerically controlled oscillator 113.

[0018] _{cos (θ-θ ref) =} cosθcosθ ref + sinθsinθ ref sin (θ-θ ref) = sinθcosθ ref -cosθsinθ ref where, cos [theta], sin [theta is the waveform of the transmitted data clock d stored in the waveform memory 111, cosθ _ref , sinθ
_ref is a complex reference signal generated by the numerical control generator 113. During the integration time T, the integrator 115 outputs the output cos (θ−θ _ref ), sin (θ−
θ _ref ) are integrated, and the phase angle θ is calculated by the ATAN2 calculator 116.

[0019] ^{θ = tan -1 {Σsin (θ} -θ ref) / (Σcosθ-θref)} "0 ≦ θ <2π" theta _ref is transmitted for the received frame detection timing b As noted above data clock d Becomes zero at the center of the waveform, and the phase angle θ obtained from the integration value of the integration time T means the phase of the transmission data clock d sampled at the reception frame detection timing b. Therefore, assuming that the measurement phase resolution is δθ and the measurement phase is θ, the measurement delay time resolution ｛(1 / f _TX ) · (δθ / 2
π)｝, a delay time measuring device having a maximum measurement delay time range (1 / f _TX ) is realized.

The arithmetic unit 8 calculates the phase measurement value θ (k) (Q2 in FIG. 1) and the sampling frame count value X (k)
(Q1 in FIG. 1) is input, and the following calculation is performed to calculate the delay time measurement value T (k) (Q3 in FIG. 1).

T (k) = {θ (k) + 2πX (k)} / 2πf _TX “SEC” As an additional function, θ (k−1), X
By storing (k-1), the reception frame period P (k) can be calculated.

P (k) = ｛θ (k) + 2πX (k) −θ
(K-1) + 2πX (k-1)} / {2πf _TX }

[0023]

As described above, according to the present invention, in a distance measuring apparatus using a fixed data pattern such as a frame synchronization pattern, a transmission fixed data pattern at a detection timing of a reception fixed data pattern such as a reception frame synchronization pattern is provided. The counter (transmission frame counter etc.) is sampled and the transmission data clock phase is measured.
By combining the two measurement values, it is possible to improve the distance measurement resolution and increase the maximum distance measurement range.

Further, by using this method, the non-measurement time required in the conventional delay time measurement is not required, and a characteristic having a function of measuring the reception frame period is provided.

For the purpose of sampling and measuring the phase of the transmission data clock at the reception fixed data pattern timing (in the embodiment, the reception frame synchronization timing), the transmission data clock frequency is set by a numerically controlled oscillator instead of using the reception data clock. This means that the frequency of the transmission / reception data clock may be different. In other words, it is possible to allow the received data clock to deviate from the transmitted data clock due to the Doppler shift effect in the transmission path. Further, there are cases in which various variable tone modulation systems having different data clocks are used as the transmission path. Even distance measurement became possible.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention.

FIG. 2 is a time chart showing signals of respective parts in the embodiment of FIG.

FIG. 3 is a block diagram showing a conventional device.

4 is a time chart showing signals of respective parts in the conventional device of FIG. 3;

[Explanation of symbols]

 Reference Signs List 1 Reference clock source 2 Frame pattern generator 3 Transmission line 4 Bit clock recovery circuit 5 Frame pattern detection circuit 6 Measurement gate generator 7 High-speed counter 8 Operation circuit 9 Transmission frame counter 10 Sampler 11 Transmission clock sampling phase measurement unit 111 Waveform memory 112 T / 2 delay circuit 113 Numerically controlled oscillator 114 Complex multiplier 115 Integrator 116 Atan2 calculator

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) G01S 7/00-17/95 H04L 7/00-7/10 G04F 10/04

Claims (2)

(57) [Claims] 1. A transmission side transmits a data pattern based on a transmission timing of a fixed data pattern to a transmission line, and a reception side reproduces a data clock and detects the fixed data pattern. In the distance measuring device that measures a delay time generated in the transmission line by measuring a delay time between detection of the transmission timing and the transmission timing, and measures a distance of the transmission line based on the delay time, The count value obtained by sampling the contents of the fixed data counter at the detection timing of the receiving fixed data pattern is divided by the transmission clock frequency.
Get the coarse delay time from the calculated value, and acquire a high-resolution delay time from the data obtained by means for measuring the phase of the clock of the transmitting side in the received fixed data pattern detection timing, the high-resolution delay and the coarse delay time A distance measuring device using a fixed data pattern, wherein a distance calculated by combining time and a time is output as a distance of a transmission path. 2. The communication system according to claim 1, wherein the fixed data pattern is a frame synchronization pattern, and the fixed data counter is a frame counter. Distance measuring device using fixed data pattern.